The subject invention relates to and is a further development of wheel-locking devices of the kind intended to secure vehicles on movable platforms which are equipped with a stop member which may be raised from the movable platform for engagement with the wheel. Wheel-locking devices of this kind also comprise a bow intended to be applied over the wheel. In its raised position, the stop member is supported against a shoulder which prevents further pivoting of the stop member. The bow is articulated to a rigid, telescopically extensible arm which comprises a controllable blocking mechanism, the latter arranged to prevent extension of said telescopic arm beyond a pre-determined, set vertical position but at the same time to allow retraction of said arm. In its applied position over the tyre, the bow rests on the wheel and supports said arm in its set vertical position as a consequence of the weight of the movable part of said arm and its own weight.